This proposal is a reapplication from the University of Texas (UT) Southwestern Medical Center at Dallas to participate with the NICHD under a cooperative agreement (RFA: HD-04-010) in an ongoing multicenter clinical program, the Cooperative Multicenter Neonatal Research Network (NRN). The NRN is designed to perform interventional and observational clinical studies in newborns, particularly low birth weight infants. The UT Southwestern site has been a member of the NRN since its inception in 1986. Pablo J. Sanchez, MD will serve as the Principal Investigator (PI), while the Alternate and Follow-up PIs remain Walid A. Salhab, M.D. and Roy J. Heyne, M.D. As a clinical center of the NRN, UT Southwestern has the necessary academic, research and clinical infrastructure already in place that will assure continued excellence in the performance of the clinical studies of the NRN. The Neonatal-Perinatal division of UT Southwestern has demonstrated a strong commitment to clinical research, and in this endeavor, it has the strong support of the Pediatric Department at UT Southwestern as well as of its clinical facilities, Parkland Memorial Hospital (PMH) and Children's Medical Center. PMH is the teaching facility of UT Southwestern where the clinical studies pertaining to this RFA will be performed. It boasts the largest inborn delivery service in the United States, with over 15,000 deliveries every year. The Obstetric Department of UT Southwestern and PMH is part of the Maternal Fetal Medicine Unit, and its obstetric service is highly integrated within the health care delivery services of targeted communities of Dallas, assuring a continued source of diverse patients for clinical studies. This patient population is predominantly Hispanic, an underserved but increasing population whose inclusion in clinical trials is essential and desired in order to reduce the health disparities that plague this ethnic group. In addition, UT Southwestern has a proven track record within the NRN, as evidenced by its well organized clinical research system with a high percentage of eligible infants enrolled in randomized trials, excellence in conducting the studies, and complete data acquisition. Follow-up of study infants is integrated within the infant's medical home at Children's Medical Center, and the follow-up rates for these infants exceed 90 percent, among the highest in the NRN. Finally, the PI of this proposal has extensive experience in the performance and conduct of multi-center, randomized clinical trials. By virtue of being board certified in both Neonatology and Pediatric Infectious Diseases, Dr. Sanchez will provide expertise to the NRN on issues in neonatal infectious diseases, a vexing problem among low birth weight infants. This will lead to the design of key studies such as the concept proposal on management of late-onset infections that ultimately may lessen the impact of infection on long-term neurodevelopmental disabilities among these high-risk infants.